This invention relates to an implantable prosthesis, comprising a multilayer molded elastomer shell, from which one or more of the layers are made of an elastomer with different chemical or physical properties, and which is afterwards filled with a liquid or a gel. Particularly, this invention relates to a prosthesis in which the differentiated layers are made visible by means of fabricating them with a different color material, so the differentiated layers can be easily identified in the final product by mere observation, providing a greater degree of safety of the device.
Today, the augmentation and reconstruction of the human breast requiring the use of an implant, as well as the use of soft tissue implants in other parts of the human body, have become a fairly common practice in the craft of plastic and reconstructive surgery. Typical long-term implantable devices, which are often selected for these procedures, include round, anatomical or molded silicone gel filled shapes. In recent years, the implants used for these procedures have raised concern with respect to the possibility of silicone gel bleeding through the implant shell after the implantation procedure. This concern was addressed in the prior art by the inclusion of a low diffusion barrier layer that would impede or diminish the bleeding or diffusion of the low molecular silicone particles of the silicone filler through the shell.
Conventional silicone implant shells are multilayered. Specifically, such shells include several layers and one or more inner barrier layers which are able to substantially resist gel bleeding, usually sandwiched between the outer and inner layers, but which may be located in any position in the shell structure. Some of the silicone filled breast implants include a low diffusion silicone elastomer shell made with layers of a dimethyl-diphenyl silicone elastomer, having a diphenyl polymer mole percentage of around 5%, and a barrier layer of dimethyl-diphenyl silicone elastomer having a diphenyl polymer mole percentage of around 15%. Fluor and other chemistries are also used as low diffusion silicone elastomer layers.
U.S. Pat. No. 4,455,691 discloses a gel-filled breast implant including a layered silicone elastomer shell made with outer layers of a dimethyl silicone elastomer and an intermediate barrier layer made of the reaction product of polydimethylsiloxane and either 3,3,3-trifluoropropylpolysiloxane, diphenylpolysiloxane or methylphenylpolysiloxane.
European Patent EP0030838 describes a silicone gel-filled silicone rubber article which is a flexible silicone rubber container filled with a silicone gel composition that includes an essentially continuous barrier layer of a fluorine-containing organopolysiloxane located between the container wall and the silicone gel composition to reduce the tendency of unreacted components present in the silicone gel to exude or bleed to the surface of the article.
Even though the performance of such barrier layers is considered acceptable at their present state of development, a serious problem persists in the use of this devices, both at the manufacturing and operating room levels, which is the impossibility for quality control personnel and medical staff of easily identifying the presence of the important low diffusion barrier layers within the complete prosthesis, without the use of impractical specialized equipment or without the use of destructive tests.
The same situation exists for many soft tissue implants where the same general fabrication technics are employed, i.e. breast, calf, gluteus, penile, testicular, nasal implants, and tissue expanders.